The present invention relates to a method for producing a semiconductor device using a semiconductor having crystalline.
A thin film transistor (TFT) and a thin film diode (TFD) using a crystalline silicon thin film semiconductor are well known. The TFT and TFD are constructed by forming a thin film semiconductor on an insulating substrate or an insulating surface formed on a semiconductor substrate. The TFT is used in various integrated circuits. In particular, The TFT may be used as a switching element to be formed in each pixel of an active matrix type liquid crystal display device, a driver element formed in a peripheral circuit portion, and an element of a three dimensional integrated circuit.
To obtain a crystalline silicon film used in such element, a method for heating an amorphous silicon film at 600.degree. C. or higher is well known. In this method, a crystalline silicon film is obtained by solid-phase-growing a silicon film having an amorphous state (an amorphous silicon film). Also, to obtain a crystalline silicon film, a method for melting a silicon film by irradiating a laser light or an intense light corresponding to the laser light and then cooling the silicon film for solidification is well known.
However, a silicon film obtained by these methods is polycrystalline. Therefore, since there are grain boundaries in the silicon film, characteristics of a TFT having such silicon film are inferior to that of a TFT having a single crystalline silicon film. In addition, since a generating position of grain boundaries cannot be adjusted, variations in characteristics of TFTs to be formed are extremely large.